HPD has already been used in human subjects for tumor localization and photoradiation treatments. HPD labeled with MN++ retains to tumor localization property and can be used as an MRI contrast agent. A number of tumor bearing animals will be injected with Mn-HPD and will be scanned at different intervals. The purpose of this study will be to determine whether useful concentrations of this compound can be achieved for MRI and at what time these concentrations occur after the injection. Also, we will study the relative concentration in tissues other than tumorous and finally will aim to determine the minimum dose needed to change the signal intensity of the tumor relative to adjacent normal tissues. A dose response curve in time will also be determined by scanning every 24 hours for several consecutive days.